Homework Help: Help for physics problem

1. Dec 5, 2005

suzi

Suppose asteroids are made almost entirely of iron. What's the largest asteroid you could run right off, flying into space, never to return? (density of iron = 7874 kg/m^3)

2. Dec 5, 2005

dicerandom

Have you made a first attempt at the problem? What did you try? What factors do you think will be relevant to the solution?

3. Dec 5, 2005

suzi

I have tried using mas = density x volume, where volume = 4/3pi r^3 but I don't know how to find the radius if the size of the asteriod is unknown.

4. Dec 5, 2005

dicerandom

Well that's the thing, they want you to find how large the asteroid can be. Assuming that the asteroid is spherical is a good start, now you need to think about your other condition. You want to be able to get up to running speed (about 10 meters per second, if you happen to be a world-class sprinter) and then go flying off the asteroid, never to return. This is termed an "escape velocity," meaning that it's how fast you need to be going in order to escape the gravitational potential of the body.

Hope this helps :)

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